The present invention is directed to vascular catheters, and more particularly to a catheter introducer which can be used in an antegrade, as well as a retrograde medical procedure.
One of the major causes of morbidity and mortality in modern times is the frequent occurrence of vascular disease. This disease expresses itself in heart attacks, strokes, lower extremity occlusive disease, and aneurysmal disease. The predominant cause of the vascular disease is atherosclerosis, which arises from localized plaque accumulation at various sites in the vascular system, and particularly in the arterial network of a person. Plaque accumulation is caused by deposition of fat, lipid, and the like substances, on the interior walls of blood vessel, which, over time, leads to narrowing of the vascular lumen, a phenomenon medically known as "stenosis". As a result, blood flow is restricted and the person's health may be at serious risk, depending upon various other clinical and health-related factors. In fact, it has been reported that cardiovascular disease is the leading cause of mortality in the developed world and that in the U.S. alone there are approximately 1 million deaths attributable to this disease.
Although atherosclerosis is commonly associated with coronary arteries that feed the heart, other peripheral blood vessels, such as carotid and lower extremity arteries are equally susceptible to plaque formation. As noted above, atherosclerosis is caused by localized plaque build up at certain vulnerable sites in the vascular system, rather than from diffusion. In this regard, the coronary arteries, carotid bifurcation, infrarenal abdominal aorta, and iliofemoral vessels are particularly susceptible, while the thoracic aorta, common and distal internal carotid, mesenteric, renal, intercostal, mammary, and upper extremity arteries tend not to be severely affected.
Numerous techniques for opening constricted blood vessels have been proposed and are currently being used by the medical community. Many devices are also available for use in these techniques. One of the widely used and accepted techniques is known as "balloon angioplasty". This technique involves introducing a catheter through a blood vessel to access the site of plaque formation. The catheter at its tip includes a balloon which is selectively inflated at the site to push or flatten the plaque against the walls of the blood vessels. This results in dilation (or dilatation) of the vessel lumen thereby improving the blood flow. A stent is commonly positioned subsequent to dilatation to prevent plaque regression and for maintaining the integrity of the vessel. Other approaches to dilatation of the blood vessels include, using a cutting or abrasive tool to remove the plaque, using an electric spark to burn through the plaque, and using laser to burn or remove portions of the plaque.
A typical angioplasty procedure is performed by retrograde (upstream of blood flow) introduction of a guidewire from the groin area of a person. An appropriate balloon angioplasty catheter is then advanced over the guidewire to reach the site of plaque formation and then dilatation of the same. This procedure works well where the lesion or plaque formation is present only at one location. However, tandem localized lesions causing lower extremity ischemia may exist in the iliac arterial system, as well as in the superficial femoral artery, and typically at the Hunter's canal. Early in the atherosclerotic disease process, the lesions tend to produce stenosis of the main arterial channel and later in the disease process, segmental arterial lesions or occlusions are encountered.
The balloon angioplasty of iliac arterial stenoses are typically performed by puncturing the common femoral artery on the same side as the lesion and advancing a guidewire across the lesion, followed by placement of an appropriate balloon angioplasty catheter across and dilatation of the same. In the event, the placement of a stent is required across an iliac artery stenosis, a similar approach is taken. In other words, a catheter is introduced from a convenient location that is below the lesion.
As noted previously, segmental occlusions of blood vessels are commonly encountered. For example, one lesion may be found in the iliac arterial system, and another lesion may be found in the superficial femoral artery which is downstream with regards to blood flow. The dilatation of the lesion in the superficial femoral artery requires an antegrade puncture of the ipsilateral common femoral artery, or one may come around the aortic bifurcation from the contralateral femoral artery and then advance a long guidewire across the stenosis in the superficial femoral artery. Neither of these procedures is preferable from a medical or a patient's point of view. From a medical standpoint, both of these approaches require a second cannulation, either an antegrade puncture of the ipsilateral femoral artery or a puncture of the contralateral femoral artery. The second cannulation generally cannot be done immediately after performing angioplasty of the first lesion, for example, in the iliac arterial system, since the first puncture is still fresh and not fully healed. In other words, the second cannulation requires a delay of at least 72 hours, and preferably a delay of at least one week, to allow the first puncture to fully heal. As a result, the patient has to be brought back for the second angioplasty procedure, or requires following a less preferable and difficult approach of the second lesion in the superficial femoral artery from the contralateral femoral artery across the aortic bifurcation.
Both of these procedures can be extremely difficult and cumbersome and are less preferable to patients, as the patient either has to return for a second procedure or encounter two punctures during one procedure, one on each side. The contralateral approach is particularly not preferable from a surgeon's viewpoint, as it requires the use of a long guidewire from one side of a patient to the other and thus leads to maneuverability problems. In addition to being difficult and less preferable to patients and surgeons, these procedures add cost to the overall angioplasty of tandem or segmental lesions in a patient.
Various catheters are currently available for use by the medical community and illustrative examples are shown in U.S. Pat. Nos. 4,549,879 to Groshong et al.; 4,671,796 to Groghong et al.; 4,701,166 to Groshong et al.; 5,098,392 to Fleishhacker et al.; 5,364,376 to Horzewski et al.; 5,531,700 to Moore et al.; 5,571,087 to Ressemann et al.; and, 5,624,396 to McNamara et al. These catheters are not concerned, however, with dilatation of tandem lesions during one medical procedure.
In view of the disadvantages associated with the conventional techniques, there is a need in the industry for a device and technique which allows a surgeon to perform dilatation of tandem or segmental lesions in a patient during one surgical procedure and by making only one puncture of a blood vessel.